This invention relates to wideband compressive receivers. More particularly, the invention addresses itself to such receivers designed to rapidly and accurately locate a single frequency signal in a wideband frequency space using a surface acoustic wave (SAW) device in a time-multiplexed fashion.
The use of signal compression techniques and dispersive delay lines in the location of radio signals of an unknown but constant frequency is known in the art. The application of multiple SAW devices to perform the function of signal dispersion and compression, though more contemporary, is also a technique known in the art.
The traditional approach to the design of wideband compressive receivers entails the application of two delay lines in conjunction with the associated electronics. The function of the first delay line is to generate the local oscillator frequency sweep (chirp) signal. After appropriate mixing with the unknown frequency signal being received, the resultant signal is applied to a compressive delay line to extract information on the frequency of the received signal.
As the bandwidth within which the unknown signal could lie increases, the complexity and expense associated with using two matched delay lines, whether SAW devices or otherwise, becomes prohibitive. The wide frequency band makes it very difficult and expensive to accurately match the dispersive and compressive nature of delay lines in terms of their nonlinearities in the slope of delay time versus frequency.